Is this Do-able?

Maybe if you want your experience in that part of Italy to be primarily of riding transit everywhere and not seeing any real sites.

In baseball, after you hit the ball, the point is to touch as many bases as you can, as quickly as you can.

I don't travel all the way to Italy to play baseball.

But for some folks it's more about adding items to their "been there" list than having a laid back vacation.

It's not for me to judge. Whatever floats your boat...er...hydrofoil.

I would check on that hydrofoil from Salerno to Sorrento. I know there's one from Naples but I would double check any from Salerno. Next, why take a bus from Paestum to Salerno when you can take a one-hour Trenitalia train from Paestum to Pompeii. Note that this Pompeii train stop is not the tourist one served by the Circumvesuviana train so you might have to taxi to the tourist entrance. Then, you can take the Circumvesuviana train to Sorrento. Then, you could hydrofoil to Naples. It's a long day.

You knew the answer when you asked. You know it is not. Pompeil is not something that you drive by and say I have seen it. What is the purpose of this drive by trip?

Helen,
I think we need more information on what you want to see. Since I would like to believe hubby is right here is what I assume. You are both archeological buffs and that is your primary reason for seeing Italy. You have about 6 to 8 hours of travel and all you really care about is Pompeii. With about 4 hours in Pompeii Scavi you can see about half of it if you are efficient. this gives you 12 hour day and arrive in Cassino in time for dinner, they eat very late in southern Italy.

I have assumed that you spent the previous day touring Paestum and that you bought picnic supplies before you left Paestum so you could picnic in Pompeii. Salerno holds no interest for you and the Amalfi coast should be treated like Chevy Chase at the Grand Canyon, uh huh uh huh. Sorrento is just a transportation hub and Naples despite the museum that holds much of Pompeii's treasures should be got through as quickly as possible.

I think you should tell your hubby that he is right it is possible but it is also possible for you to see it with another man but that is not how he should plan it.

Helen, here's a win-win solution: let Hubby do it his way, you do it your way--you don't want to be dragged through a day like that, why? I'll bet Ron of Rome will be your guide and give you the more enjoyable kind of experience that you deserve. You and Hubby can compare notes in a couple of days when you get back from your tour. (Just kidding, Ron, not trying to get you in trouble on the home front.) Helen - it's 6 am Ron's time so he won't be able to disavow my volunteering of his services until he sees this tomorrow.

I would be so tired doing this that I wouldn't really see anything let alone enjoy any of it...

I'd like to know the answer to the "why" ? question! What is it that you want to accomplish?